The present invention generally relates to a method and associated apparatus for reducing the time required to scan an incoming satellite transmission power spectrum for available signals and to determine the characteristics of those signals. The frequency range of interest is scanned in narrow slices to determine approximate input power within each slice. Center frequencies and symbol rates of individual transponders are then estimated based upon these input power approximations.
This section is intended to introduce the reader to various aspects of art, which may be related to various aspects of the present invention that are described below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present invention. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.
Satellite television receiving systems generally comprise an outdoor unit, comprising a dish antenna and a low noise block (LNB) amplifier, and an indoor unit, commonly referred to as an integrated receiver decoder (IRD), which may be in the form of a set-top box. The set-top box generally comprises at least one tuner and a signal processing section, and is used to tune desired television signals.
In some environments, the set-top box can be pre-programmed with certain information regarding the signals to be received, such as possible center frequencies, bandwidths, and symbol rates. In other cases, it is necessary for a set-top box to scan the input signals for channels and their configurations.
Scanning to determine the input configuration is commonly performed using a brute force method. In one such method, the tuner is tuned to a frequency near the low end of the input frequency spectrum, a symbol rate is chosen, and an attempt is made to lock a signal. If a signal cannot be locked, the symbol rate is changed and another attempt is made. After some number of changes in the symbol rate, the frequency is then increased by some interval to the next potential channel frequency and the process is repeated.
In transmission environments with a wide range of frequencies and varying signal parameters, such as a satellite television system with hundreds of potential channels spanning Ka and Ku bands, however, this approach can be extremely time consuming. Many hours may be required for a full scan, which can be required at initial device activation, significantly delaying use of the device by the consumer.
As satellite capacity is added and greater variations in transmission parameters are allowed, the time required increases even further, becoming unacceptable to the user. A method is therefore needed to improve the satellite set-top box scanning process. The invention described herein addresses this and/or other problems.